Last Saturday’s mass shooting was both foreseeable and preventable, but not in the manner you might think. First, let’s start with what we know about Saturday’s events: 1. An 18-year-old shot and killed black people that he targeted 2. The individual (we won’t use his name so as not to empower him) was the subject of a mental-health investigation last year while in high school 3. We don’t know what radicalized him, but we do know he was very active on social media 4. We can also reasonably assume that this individual’s perception of reality was guided by confusing and...